OBJECTIVE: To evaluate, primarily, the accuracy of plain radiography (X-ray) in diagnosing apophyseal avulsion fractures in adolescent soccer players, using magnetic resonance imaging (MRI) as the gold standard. As secondary objectives, we investigated associations between findings on X-ray, MRI, and power Doppler, as well as the imaging features that distinguish avulsion fractures from apophysitis.
MATERIALS AND METHODS: This was an observational cross-sectional study involving 33 male athletes 9–17 years of age with clinical suspicion of an apophyseal avulsion fracture. Imaging examinations were performed within the first 24 h after the trauma. We evaluated diagnostic reproducibility among readers, the accuracy of X-ray compared with MRI, and the associations between findings from different imaging methods.
RESULTS: We found that X-ray had an accuracy of 56.0%, with high specificity (71.4%) and positive predictive value (81.8%), although its sensitivity and negative predictive value were relatively low (50.0% and 35.7%, respectively). The power Doppler result was significantly associated with avulsion fractures detected on MRI (p = 0.0144). Avulsion fractures were associated with periphyseal edema and intermuscular fluid collections, while apophysitis was associated with bone marrow edema.
CONCLUSION: X-ray is useful for confirming, but not for excluding, avulsion fractures. Power Doppler and MRI contribute to the differential diagnosis.

Keywords: Radiography; Magnetic resonance imaging; Fractures, avulsion; Ultrasonography, Doppler; Soccer/injuries.